Methods for forming spacers and related structures

ABSTRACT

Methods for patterning and forming structures, as well as related structures and systems are disclosed. The methods comprise forming a liner on sidewalls of a patterned resist. The patterned resist comprises a first metal, and the liner comprises a second metal.

FIELD OF INVENTION

The present disclosure generally relates to the field of lithography,and particularly to the field of extreme ultraviolet lithography.

BACKGROUND OF THE DISCLOSURE

With the constant scaling of semiconductor devices, and the associatedreduction of the critical dimensions (CD) of their constituentstructures, conventional extreme ultraviolet (EUV) lithography scannersare reaching their resolution limit: certain types of isolated structurepatterns (in particular, contacts and holes for vias), cannot be printedat the target critical dimensions of less than 20 nm. Accordingly, theactual critical dimension after EUV lithographic exposure is about 20nm, higher than targeted critical dimension (CD).

With the scaling down of EUV feature size, new resist types wererecently introduced. In particular, Metal Organic Resist (MOR) aregaining traction as they exhibit higher etch resistance which allows forthinner photoresist layers and thus easier pattern transfer with lessdefectivity (especially at the smallest CDs and pitch). However, theseresists still suffer from the same EUV resolution limitation (forinstance minimum printed CD size ˜20 nm for isolated Contact/Holesstructures) as their Chemically Amplified Resist (CAR) counterparts (Cbased photoresist).

The presently disclosed methods and structures provide a solution for atleast some of the above-mentioned challenges.

SUMMARY OF THE DISCLOSURE

Various embodiments of the present disclosure relate to methods forforming structures. The methods comprise providing a substrate to areaction chamber. The substrate comprises a patterned resist. Thepatterned resist comprises a first metal. The patterned resist furthercomprises a plurality of patterned features and a plurality of recesses.The plurality of recesses comprise sidewalls and bottom portions. Themethods further comprise forming a liner on the sidewalls. The linercomprises a second metal.

Further described herein are methods for forming a pattern on asubstrate. The methods comprise forming a resist on a substrate. Theresist comprises a first metal. The method further comprises partiallyexposing the substrate to radiation through a mask. Accordingly, exposedresist portions and unexposed resist portions are formed. The methodfurther comprises selectively removing one of the exposed resistportions and unexposed resist portions. Thus, a patterned resist isformed. The patterned resist comprises the first metal. The patternedresist further comprises a plurality of patterned features and aplurality of recesses. The plurality of recesses comprise sidewalls andbottom portions. The method further comprises providing the substrate toa reaction chamber. The method further comprises forming a liner on thesidewalls. The liner comprises a second metal.

In some embodiments, the resist comprises an EUV resist and theradiation comprises EUV radiation.

In some embodiments, the first metal and the second metal are the same.

In some embodiments, the liner is further formed on the patternedfeatures and the bottom portions of the recesses.

In some embodiments, the step of forming the liner is further followedby etching the liner. Thus, the liner is removed from the patternedfeatures and the bottom portions of the recesses, and forming spacers onthe sidewalls.

In some embodiments, at least one of the first metal and the secondmetal is selected from Sn, In, Sb, Ti, Al, Zn, Hf, and Zr.

In some embodiments, the liner and the resist have a substantiallyidentical composition.

In some embodiments, the liner and the resist have a substantiallyidentical etch rate.

In some embodiments, at least one of the resist and the liner compriseone or more of a pnictogen, a chalcogen, and a halogen.

In some embodiments, the resist and the liner comprise the same metaloxide.

In some embodiments, forming the liner comprises providing a precursorand a reactant to the reaction chamber.

In some embodiments, forming the liner comprises forming a plasma.

In some embodiments, the precursor and the reactant are simultaneouslyprovided to the reaction chamber.

In some embodiments, forming the liner comprises executing a cyclicalprocess. The cyclical process comprises a precursor pulse and a reactantpulse. The precursor pulse comprises exposing the substrate to theprecursor. The reactant pulse comprises exposing the substrate to thereactant.

In some embodiments, the precursor comprises at least one of a metalalkylamine, a metal alkyl, and a metal halide.

In some embodiments, the reactant comprises oxygen.

Further described herein is a system that comprises one or moreprecursor sources, a reaction chamber operationally coupled with the oneor more precursor sources, and a controller. The controller is arrangedfor causing the system to carry out a method as described herein.

Further described herein is a structure that comprises a substrate, apatterned resist, and a liner. The patterned resist comprises a firstmetal. The patterned resist further comprises a plurality of patternedfeatures and a plurality of recesses. The plurality of recesses comprisesidewalls and bottom portions. The liner is positioned on the sidewalls.The liner comprises a second metal.

Further described herein is a structure that is formed by means of amethod as described herein.

These and other embodiments will become readily apparent to thoseskilled in the art from the following detailed description of certainembodiments having reference to the attached figures; the invention notnecessarily being limited to any particular embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE FIGURES

A more complete understanding of exemplary embodiments of the presentdisclosure can be derived by referring to the detailed description andclaims when considered in connection with the following illustrativefigures.

FIG. 1 shows a reactor in which at least embodiments of methodsaccording to the present disclosure can be executed.

FIG. 2 illustrates a system (200) in accordance with additionalexemplary embodiments of the disclosure.

FIGS. 3A and 3B show substrates comprising a liner and a spacer.

FIG. 4 shows a flow chart of an exemplary patterning process inaccordance with certain embodiments of the present disclosure.

FIGS. 5-8 shows flow charts of processes for forming liners inaccordance with certain embodiments of the present disclosure.

FIGS. 9A-9C and 10A-10B show exemplary pulsing schemes for use inmethods according to certain embodiments of the present disclosure.

FIGS. 11-13 show exemplary systems for use in methods according tocertain embodiments of the present disclosure.

It will be appreciated that elements in the figures are illustrated forsimplicity and clarity and have not necessarily been drawn to scale. Forexample, the dimensions of some of the elements in the figures may beexaggerated relative to other elements to help improve understanding ofillustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The description of exemplary embodiments of the present inventionprovided below is merely exemplary and is intended for purposes ofillustration only; the following description is not intended to limitthe scope of the invention disclosed herein. Moreover, recitation ofmultiple embodiments having stated features is not intended to excludeother embodiments having additional features or other embodimentsincorporating different combinations of the stated features.

As used herein, the term substrate may refer to any underlying materialor materials including and/or upon which one or more layers can bedeposited. A substrate can include a bulk material, such as silicon(e.g., single-crystal silicon), other Group IV materials, such asgermanium, or compound semiconductor materials, such as GaAs, and caninclude one or more layers overlying or underlying the bulk material.For example, a substrate can include a patterning stack of severallayers overlying bulk material. The patterning stack can vary accordingto application and can include, for example, a hard mask, such as ametal hard mask, an oxide hardmask, a nitride hardmask, a carbidehardmask, or an amorphous carbon hardmask. Further, the substrate canadditionally or alternatively include various features, such asrecesses, lines, and the like formed within or on at least a portion ofa layer of the substrate.

In this disclosure, gas may include material that is a gas at normaltemperature and pressure, a vaporized solid and/or a vaporized liquid,and may be constituted by a single gas or a mixture of gases, dependingon the context. A gas other than the process gas, i.e., a gas introducedwithout passing through a gas distribution assembly, such as ashowerhead, other gas distribution device, or the like, may be used for,e.g., sealing the reaction space, and may include a seal gas, such as anoble gas.

In some cases, such as in the context of deposition of material, theterm precursor can refer to a compound or compounds that participates inthe chemical reaction that produces another compound, and particularlyto a compound that constitutes a film matrix or a main skeleton of afilm, whereas the term reactant can refer to a compound, in some casesother than precursors, that reacts with the precursor, activates theprecursor, modifies the precursor, or catalyzes a reaction of theprecursor; a reactant may provide an element to a film and become a partof the film. In some cases, the terms precursor and reactant can be usedinterchangeably.

The term cyclic deposition process or cyclical deposition process mayrefer to the sequential introduction of precursors (and/or reactants)into a reaction chamber to deposit a layer over a substrate and includesprocessing techniques such as atomic layer deposition (ALD), cyclicalchemical vapor deposition (cyclical CVD), and hybrid cyclical depositionprocesses that include an ALD component and a cyclical CVD component. Inother cases, the processing techniques may include a plasma process suchas plasma enhanced CVD (PECVD) or plasma enhanced ALD (PEALD), which maybe preferred in some implementations because they allow working at lowertemperatures.

The term atomic layer deposition may refer to a vapor deposition processin which deposition cycles, typically a plurality of consecutivedeposition cycles, are conducted in a process chamber. The term atomiclayer deposition, as used herein, is meant to include processesdesignated by related terms, such as chemical vapor atomic layerdeposition, atomic layer epitaxy (ALE), molecular beam epitaxy (MBE),gas source MBE, or organometallic MBE, and chemical beam epitaxy whenperformed with alternating pulses of precursor(s)/reactive gas(es), andpurge (e.g., inert carrier) gas(es).

Generally, for ALD processes, during each cycle, a precursor isintroduced to a reaction chamber and is chemisorbed to a depositionsurface (e.g., a substrate surface that can include a previouslydeposited material from a previous ALD cycle or other material), formingabout a monolayer or sub-monolayer of material that does not readilyreact with additional precursor (i.e., a self-limiting reaction).Thereafter, in some cases, a reactant may subsequently be introducedinto the process chamber for use in converting the chemisorbed precursorto the desired material on the deposition surface. The reactant can becapable of further reaction with the precursor. Purging steps can beutilized during one or more cycles, e.g., during each step of eachcycle, to remove any excess precursor from the process chamber and/orremove any excess reactant and/or reaction byproducts from the reactionchamber.

As used herein, the term purge or purging may refer to a procedure inwhich gas flow is stopped or a procedure involving continual provisionof a carrier gas whereas precursor flow is intermittently stopped. Forexample, a purge may be provided between a precursor pulse and areactant pulse, thus avoiding, or at least reducing, gas phaseinteractions between the precursor and the reactant. It shall beunderstood that a purge can be effected either in time or in space orboth. For example, in the case of temporal purges, a purge step can beused, e.g., in the temporal sequence of providing a precursor to areactor chamber, providing a purge gas to the reactor chamber, andproviding a reactant to the reactor chamber, wherein the substrate onwhich a layer is deposited does not move. In the case of spatial purges,a purge step can take the form of moving a substrate from a firstlocation to which a precursor is supplied, through a purge gas curtain,to a second location to which a reactant is supplied.

In this disclosure, any two numbers of a variable can constitute aworkable range of the variable, and any ranges indicated may include orexclude the endpoints. Additionally, any values of variables indicatedmay refer to precise values or approximate values and includeequivalents, and may refer to average, median, representative, majority,etc. in some embodiments. Further, in this disclosure, the termsincluding, constituted by and having can refer independently totypically or broadly comprising, comprising, consisting essentially of,or consisting of in some embodiments. Further, the term comprising caninclude consisting of or consisting essentially of. In accordance withaspects of the disclosure, any defined meanings of terms do notnecessarily exclude ordinary and customary meanings of the terms.

Described herein is a method for forming a structure. The methodcomprises providing a substrate to a reaction chamber. The substratecomprises a patterned resist. The patterned resist comprises a firstmetal. The patterned resist further comprises a plurality of patternedfeatures and a plurality of recesses. The recesses comprise sidewallsand bottom portions. The method further comprises forming a liner on thesidewalls. The liner comprises a second metal.

Further described herein is a method for forming a pattern on asubstrate such as a wafer. The method comprises forming a resist on thesubstrate. Exemplary resists include EUV resists, i.e. resists that aresensitive to extreme ultraviolet light. The resist comprises a firstmetal. The method further comprises partially exposing the substrate toradiation through a mask. When a substrate is partially exposed, certainparts of the substrate are illuminated while other parts are not. Thus,exposed resist portions and unexposed resist portions are formed. Themethod further comprises selectively removing one of the exposed resistportions and the unexposed resist portions. It shall be understood thatboth positive resists and negative resists can be suitably employed.Thus, a patterned resist is formed. The patterned resist comprises thefirst metal. The patterned resist further comprises a plurality ofpatterned features and a plurality of recesses. The plurality ofrecesses comprise sidewalls and bottom portions. The method furthercomprises providing the substrate to a reaction chamber. Then, a lineris formed on the sidewalls. The liner comprises a second metal.

Thus, described herein are methods for forming spacers, and methods forforming a pattern on a substrate. Further described herein are relatedstructures and systems. The spacers can be advantageously employed inthe context of patterning semiconductor substrates, for example usingextreme ultraviolet (EUV) light. In particular, the spacersadvantageously allow reducing the critical dimension of features thatcan be patterned. Accordingly, patterns having a critical dimension ofless than 20 nm can be efficiently formed, thereby circumventing currentEUV resolution limits.

In addition, as the spacer formation can be suitably performed directlyafter lithography, subsequent etch steps can use a “straight”anisotropic etch, i.e. an anisotropic etch perpendicular to thesubstrate plane with limited use of polymerizing gas and no tapering,thus potentially improving features uniformity and placement and limitdefects. The presently disclosed methods can additionally result inpatterns having a low roughness, reduced costs, and increasedthroughput.

Furthermore, a wide variety of materials, e.g. metal centers andco-reactants, can be employed such that the liner composition can bespecifically selected such that a liner is formed which has a similar oridentical etch rate as the patterned resist on which it is formed.

A method as described herein can employ any suitable resist. In someembodiments, the resist is a resist that is sensitive to extremeultraviolet radiation (EUV resist). Suitably, the radiation employed forpartially exposing the substrate to radiation through a mask. An EUVphotoresist layer may include any suitable photoresist, such asmolecular, metal oxide, or chemically amplified photoresist. It shall beunderstood that the photoresists can be formed using any suitabledeposition technique, including chemical vapor deposition (CVD),plasma-enhanced chemical vapor deposition (PECVD), atomic layerdeposition (ALD), and plasma-enhanced atomic layer deposition (PEALD).

In some embodiments, the resist comprises a metalorganic resist (MOR).Suitable metalorganic resists include tin oxycarbide and indiumoxycarbide resists. Such resists can be formed using a variety oftechniques including spin coating, chemical vapor deposition,plasma-enhanced chemical vapor deposition, atomic layer deposition,molecular layer deposition, and plasma-enhanced atomic layer deposition.

In some embodiments, the resist comprises a metal oxide resists.Suitable metal oxide resists include tin oxide resists and indium oxideresists. Such resists can be formed using a variety of techniquesincluding spin coating, chemical vapor deposition, plasma-enhancedchemical vapor deposition, atomic layer deposition, molecular layerdeposition, and plasma-enhanced atomic layer deposition. The resist can,in some embodiments, comprise an oxide of at least one of tin, indium,and antimony.

The resist suitable comprises a material that undergoes a physical orchemical change, e.g. a change in solubility, upon exposure to one ormore kinds of electromagnetic radiation, e.g. EUV radiation.

A wide variety of materials (metal centers and co-reactants) allow forspecific tailoring of the liner layer composition to adapt to specificresist compositions and subsequent etch chemistries. Thus in someembodiments, the first and second metals are the same. Thus, the resistand the liner can comprise the same metal. In other embodiments, thefirst and second metals are different, that is the resist and linercomprise dissimilar metals, but the resist and liner do exhibit similaror identical etch rates, e.g. in a vapor-phase etch.

In some embodiments, the first metal and the second metal are the same.This can be advantageous when, for example, a liner is formed which hasa similar or identical etch rate as the patterned resist on which it isformed.

In some embodiments, the liner is further formed on the patternedfeatures and the bottom portions of the recesses. Suitably, and in someembodiments, a method as described herein then comprises a step ofanisotropically etching the liner, thus removing the liner from thepatterned features and the bottom portions, and forming spacers on thesidewalls.

It shall be understood that the density and etch resistance of the linercan be tailored by adapting the deposition parameters (for instancedeposition temperature, pressure, plasma composition, etc.), precursorselection, reactant composition, etc.

In some embodiments, at least one of the first metal and the secondmetal is selected from Sb, In, and Sn.

In some embodiments, at least one of the resist and the liner compriseone or more of a pnictogen, a chalcogen, and a halogen. In someembodiments, at least one of the resist and the liner comprises a metalpnictogen, a metal chalcogen, or a metal halide. Suitable metalpnictogens include metal nitrides. Suitable metal chalcogens includemetal oxides, metal sulfides, metal selenides, and metal tellurides.

Suitable precursors include metal precursors such as tin precursors,antimony precursors, and indium precursors. In some embodiments, theprecursor comprises an element selected from the list consisting of Sn,In, Sb, Ti, Al, Zn, Hf, and Zr. The metal precursors can, for example,comprise alkylamines, alkyls, or halides. In some embodiments theprecursor comprises a tin alkylamine such as tetrakis(dimethylamido)tin.In some embodiments, the precursor comprises an indium alkyl such astrimethylindium. In some embodiments, the precursor comprises a tinhalide such as SnI₄. In some embodiments, the precursor comprises anantimony halide such as SbCl₅.

Suitable reactants include gaseous compounds and elemental gasses thatcan react or otherwise interact with the precursor. The reaction betweena reactant and a precursor can either be thermal or it can be activatedthrough some activation means such as a plasma, hot wire, or UV light.

In some embodiments the reactant comprises oxygen. Thus, in someembodiments, the reactant comprises an oxygen reactant. Suitable oxygenreactants include O₂, O₃, and H₂O.

In some embodiments, the reactant includes a halide, such as one or moreof F, Cl, Br, and I. In some embodiments, the reactant comprises ahydrogen halide such as HF, HCl, HBr, or HI. In some embodiments, thereactant comprises an elementary halogen such as F₂, Cl₂, Br₂, or I₂.

In some embodiments, the reactant comprises a nitrogen reactant.Suitable nitrogen reactants include N₂, NH₃, N₂H₂, and forming gas.

In some embodiments, the reactant comprises a carbon reactant. Suitablecarbon reactants include alkyls such as CH₄.

In some embodiments, the reactant comprises a reducing reactant.Suitable reducing reactants include H₂.

In some embodiments, the reactant comprises a diol, such as an aliphaticor aromatic diol. Suitable diols include ethylene glycol andhydroquinone.

In some embodiments, the reactant comprises at least one of ions andradicals. The ions and radicals can be generated in a plasma, forexample in a plasma in the reaction chamber or in a remote plasma at acertain distance from the reaction chamber. When the plasma is generatedin the reaction chamber, the plasma can be a direct or an indirectplasma. A direct plasma is in direct contact with the substrate. Anindirect plasma is separated from the substrate by means of a separatorcomprising openings such as a mesh plate or a perforated plate. In someembodiments, the plasma employs a plasma gas that comprises a noble gas,or a plasma gas that comprises a noble gas and an oxygen-containing gas,or a plasma gas that comprises Ar and O₂, or a plasma gas that comprisesO₂, or a plasma gas that comprises He and O₂, or a plasma gas thatcomprises Ar.

In some embodiments, forming a liner comprises executing an atomic layerdeposition process. In such embodiments, the liner is formed bysequentially exposing the substrate to precursor and reactant. Substrateand reactant exposures can be separated by a purge. The precursor cancomprise an alkylamine such as tetrakis(dimethylamido)tin, an alkyl suchas trimethylindium, or a halide such as SnI₄ or SbCl₅. The reactant cancomprise a reactant comprising water and oxygen such as H₂O or H₂O₂.Such atomic layer deposition processes are useful, for example, forforming liners on metalorganic resists that were deposited usingplasma-enhanced chemical vapor deposition processes.

In some embodiments, forming a liner comprises executing a molecularlayer deposition process. In such embodiments, the liner is formed bysequentially exposing the substrate to precursor and reactant. Substrateand reactant exposures can be separated by a purge. The precursor cancomprise an alkylamine such as tetrakis(dimethylamido)tin, an alkyl suchas trimethylindium, or a halide such as a iodide, a bromide, orchloride. Suitable iodides include SnI₄. Suitable chlorides includeSbCl₅. The reactant can comprise a diol, e.g. an aliphatic diol such asethylene glycol or an aromatic diol such as hydroquinone. Such molecularlayer deposition processes are useful, for example, for forming linerson metalorganic resists that were formed using spin-coating.

In some embodiments, forming a liner comprises executing aplasma-enhanced atomic layer deposition process. In such embodiments,the liner is formed by sequentially exposing the substrate to precursorand a reactant. In such embodiments, the reactant comprises activespecies such as ions and radicals that were generated using a plasma.Substrate and reactant exposures can be separated by a purge. Theprecursor can comprise an alkylamine such as tetrakis(dimethylamido)tin,an alkyl such as trimethylindium, or a halide such as a iodide, abromide, or a chloride. Suitable iodides include SnI₄. Suitablechlorides include SbCl₅. As mentioned, the ions and radicals can begenerated in a plasma, for example in a plasma in the reaction chamberor in a remote plasma at a certain distance from the reaction chamber.When the plasma is generated in the reaction chamber, the plasma can bea direct or an indirect plasma. In some embodiments, the plasma employsa plasma gas that comprises a noble gas, or a plasma gas that comprisesa noble gas and an oxygen-containing gas, or a plasma gas that comprisesAr and O₂, or a plasma gas that comprises O₂, or a plasma gas thatcomprises He and O₂, or a plasma gas that comprises Ar. Suchplasma-enhanced atomic layer deposition processes are useful, forexample, for forming liners on metalorganic resists that were depositedusing plasma-enhanced chemical vapor deposition processes.

In some embodiments, forming the liner comprises providing a precursorand a reactant to the reaction chamber.

Exemplary deposition methods can be or include cyclical depositionmethods, such as ALD and pulsed CVD methods, and can include, in someuseful embodiments, indirect, direct, and remote plasma methods, whichmay include super cycle processes in which sub-cycles may be selectivelyrepeated to enhance tuning (e.g., to achieve a desired amount orconcentration of a desired element in the absorber or underlayer or thelike). A liner as described herein can be formed using thermal chemicalvapor deposition (CVD), pulsed CVD, thermal atomic layer deposition(ALD), plasma-enhanced CVD (PECVD), or plasma-enhanced ALD (PEALD). Allthese approaches may suitably provide for the deposition of thin 5 nm)liners with low non-uniformity.

In some embodiments, the liner is deposited by means of a cyclicalprocess such as a molecular layer deposition process employingalternating pulses of a metal precursor and a carbon reactant. Suitablythe metal precursor can include a metal alkylamine such astetrakis(dimethylamido)tin, and the carbon reactant can comprise analiphatic diol such as ethylene glycol or an aromatic diol such ashydroquinone. Such liners can be suitably used, for example, on tinoxycarbide resists.

In some embodiments, the liner is deposited by means of a cyclicalprocess such as a molecular layer deposition process or an atomic layerdeposition process comprising alternating pulses of a metal precursorand a carbon reactant. Suitably, the metal precursor can include a metalalkyl such as trimethylindium, and the carbon reactant can comprise analiphatic diol such as ethylene glycol or an aromatic diol such ashydroquinone. Such liners can, for example, be suitably used on indiumoxycarbide resists.

In some embodiments, forming the liner comprises forming a plasma.Various plasmas can be used, such as direct plasmas, indirect plasmas,and remote plasmas. The plasma can be generated continuously orintermittently.

In some embodiments, the precursor and the reactant are simultaneouslyprovided to the reaction chamber. In some embodiments, no plasma isgenerated while forming the liner. The substrate can, in someembodiments, be continuously exposed to precursor and reactant. In otherembodiments, the substrate can be alternatingly exposed to precursor andreactant.

In some embodiments, forming the liner comprises a cyclical process. Thecyclical process comprises a precursor pulse and a reactant pulse. Theprecursor pulse comprises exposing the substrate to the precursor. Thereactant pulse comprises exposing the substrate to the reactant.

In some embodiments, forming the liner comprises a thermal cyclicalprocess such as a thermal atomic layer deposition process. The cyclicalprocess comprises a precursor pulse and a reactant pulse. The precursorpulse comprises exposing the substrate to the precursor. The reactantpulse comprises exposing the substrate to the reactant. During a thermalcyclical process, the substrate is not exposed to plasma-generatedactive species such as plasma-generated ions or radicals.

In a thermal cyclical process, suitable precursors include metalalkylamines such as tetrakis(dimethylamido)tin, metal alkyls such astrimethylindium, and metal halides such as tin tetraiodide and antimonypentachloride.

In a thermal cyclical process, suitable reactants include oxygen andhydrogen-containing gasses or vapors such as H₂O and H₂O₂. Othersuitable reactants include oxygen-containing gasses such as O₂ and O₃.

Suitably, a thermal cyclical process employing a metal precursor and areactant that comprises hydrogen result in liners that have an etchresistance that is similar to that of metal oxide-containing resists.For example, such liners can be suitably formed on patterned metal oxideresists that are deposited using plasma-enhanced chemical vapordeposition.

In some embodiments, forming the liner comprises a molecular layerdeposition process. A molecular layer deposition process is a specificcyclical deposition process. The molecular layer deposition processcomprises a precursor pulse and a reactant pulse. The precursor pulsecomprises exposing the substrate to the precursor. The reactant pulsecomprises exposing the substrate to the reactant. During a molecularlayer deposition process, the substrate is not exposed toplasma-generated active species such as plasma-generated ions orradicals.

In a molecular layer deposition process, suitable precursors includemetal alkylamines such as tetrakis(dimethylamido)tin, metal alkyls suchas trimethylindium, and metal halides such as tin tetraiodide andantimony pentachloride.

In a molecular layer deposition process, suitable reactants includediols including alkyl diols such as ethylene glycol, 2-Butene-1,4-diol,and maleic acid; acyl halides such as succinyl chloride, fumarylchloride; and aromatic diols or triols such as hydroquinone andBenzene-1,3,5-triol.

Suitably, a molecular layer deposition process as described herein canresult in liners that have an etch resistance that is in between theetch resistance of a metal oxide resist and an organic resist. Forexample, such liners can be suitably formed on patterned resists thatcomprise a metal, oxygen, and optionally carbon, such as resists thatare deposited using spin-coating techniques or metalorganic frameworkresists comprising metallic ions and coordinated organic ligands.

In some embodiments, forming the liner comprises a plasma-based cyclicalprocess such as a plasma-enhanced atomic layer deposition process. Theplasma-enhanced atomic layer deposition process comprises a precursorpulse and a plasma pulse. The precursor pulse comprises exposing thesubstrate to the precursor. The plasma pulse comprises generating aplasma and exposing the substrate to plasma-generated active speciessuch as ions or radicals.

In a plasma-based cyclical process such as a plasma-enhanced atomiclayer deposition process, suitable precursors include metal alkylaminessuch as tetrakis(dimethylamido)tin, metal alkyls such astrimethylindium, and metal halides such as tin tetraiodide and antimonypentachloride.

During a plasma pulse, a direct plasma or an indirect plasma can beused. Suitable plasmas include noble gas plasmas such as He and Arplasmas. Other suitable plasmas include O₂ plasmas, and plasmas in whichthe plasma gas comprises a mixture of O₂ and a noble gas such as He orAr.

Suitably, a plasma-enhanced cyclical deposition process as describedherein can result in liners that have an etch resistance that is inbetween the etch resistance of a metal oxide resist and an organicresist. For example, such liners can be suitably formed on patternedresists that comprise a metal, oxygen, and optionally carbon, and thatare deposited plasma-enhanced deposition techniques such asplasma-enhanced chemical vapor deposition.

In some embodiments, the step of forming the liner is further followedby a step of etching the liner. Optionally, the step of forming theliner comprises partially etching the resist. Suitably, the step offorming the liner employs an anisotropic etch, i.e. an etch that has ahigher etch rate in a direction perpendicular to the substrate surfacecompared to directions parallel to the substrate surface. Accordingly,the liner is removed from the patterned features and the bottom portionsof the recesses, and spacers are formed on the sidewalls.

In some embodiments, the liner and the resist have a substantiallyidentical composition. The liner and resist can additionally have asimilar microstructure. For example, resist and liner can both beamorphous, or they can both have a microcrystalline structure, or theycan both have a polycrystalline structure. Advantageously, whenmicrostructure and composition are similar or substantially identical,the resist and liner can then have similar etch rates, regardless of theetchant used.

In some embodiments, the liner and the resist have a substantiallyidentical etch rate, e.g. when subject to etchants such as NF₃, BCl₃,CF₄, CHF₃, SF₆, HBr, Cl₂, and mixtures thereof. Such etchants can beemployed using RIE (Reactive Ion Etch) inside a capacitively coupledplasma (CCP), inductively coupled plasma (ICP), or remote plasmachamber. An identical etch rate could also occur with wet etching, forinstance using diluted HF or tetramethylammonium hydroxide (TMAH).

In some embodiments, the liner and the resist have a differentcomposition, but an identical etch rate.

In some embodiments, the precursor comprises at least one of a metalalkylamine, a metal alkyl, and a metal halide.

While forming the liner, the reaction chamber can be maintained at atemperature of, for example from at least 20° C. to at most 200° C., orfrom at least 50° C. to at most 300° C. While forming the liner, thereaction chamber can be maintained, for example, at a pressure of atleast 140 Pa to at most 1300 Pa. At least one of the precursor and thereactant can, for example, be provided at a flow rate of at least 200 toat most 2000 sccm. In some embodiments, a precursor pulse lasts from atleast 0.1 s to at most 15 s.

Suitably, at least one of the temperature and the pressure of thereaction chamber can be maintained at a constant value throughout amethod as described herein, for example within a margin of error of atmost 10%.

Further described herein is a system that comprises one or moreprecursor sources, a reaction chamber that is operationally coupled withthe one or more precursor sources, and a controller. The controller isarranged for causing the system to carry out a method as describedherein.

Further described herein is a structure. The structure comprises asubstrate, a patterned resist, and a liner. The patterned resistcomprises a first metal. The patterned resist further comprises aplurality of patterned features and a plurality of recesses. Theplurality of recesses comprise sidewalls and bottom portions. The lineris located on the sidewalls. The liner comprises a second metal.Advantageously, but not necessarily, the first metal and the secondmetal are identical. In some embodiments, the first metal and the secondmetal are Sn. In some embodiments, the first metal and the second metalare Sb. In some embodiments, the first metal and the second metal areIn. In some embodiments, the structure is formed by means of a method asdescribed herein.

The presently provided methods may be executed in any suitableapparatus, including in a reactor as shown in FIG. 1 . Similarly, thepresently provided structures may be manufactured in any suitableapparatus, including a reactor as shown in FIG. 1 . FIG. 1 is aschematic view of a plasma-enhanced atomic layer deposition (PEALD)apparatus, desirably in conjunction with controls programmed to conductthe sequences described below, usable in some embodiments of the presentinvention. In this figure, by providing a pair of electricallyconductive flat-plate electrodes (2,4) in parallel and facing each otherin the interior (11) (reaction zone) of a reaction chamber (3), applyingRF power (e.g. at 13.56 MHz and/or 27 MHz) from a power source (25) toone side, and electrically grounding the other side (12), a plasma isexcited between the electrodes. A temperature regulator may be providedin a lower stage (2), i.e. the lower electrode. A substrate (1) isplaced thereon and its temperature is kept constant at a giventemperature. The upper electrode (4) can serve as a shower plate aswell, and a reactant gas and/or a dilution gas, if any, as well as aprecursor gas can be introduced into the reaction chamber (3) through afirst gas line (21) and a second gas line (22), respectively, andthrough the shower plate (4). Additionally, in the reaction chamber (3),a circular duct (13) with an exhaust line (17) is provided, throughwhich the gas in the interior (11) of the reaction chamber (3) isexhausted. Additionally, a transfer chamber (5) is disposed below thereaction chamber (3) and is provided with a gas seal line (24) tointroduce seal gas into the interior (11) of the reaction chamber (3)via the interior (16) of the transfer chamber (5) wherein a separationplate (14) for separating the reaction zone and the transfer zone isprovided. Note that a gate valve through which a wafer may betransferred into or from the transfer chamber (5) is omitted from thisfigure. The transfer chamber is also provided with an exhaust line (6).

FIG. 2 illustrates a system (200) in accordance with additionalexemplary embodiments of the disclosure. The system (200) can be used toperform a method as described herein and/or to form a structure asdescribed herein.

In the illustrated example, the system (200) includes one or morereaction chambers (202), a precursor gas source (204), a reactant gassource (205), and optional further gas sources (206,208). Of course, thesystem (200) can optionally comprise even more gas sources (not shown).The system further comprises an exhaust (210) and a controller (212).

The reaction chamber (202) can include any suitable reaction chamber,such as an ALD or CVD reaction chamber.

Any one of the gas sources (204-208) can include a vessel and one ormore precursors, reactants, or other gasses as described herein. A gassource (204-208) can optionally comprise a mixing unit for mixingprecursor with one or more carrier (e.g., noble) gases. A purge gassource (not shown) can, for example, include one or more noble gases asdescribed herein. Although illustrated with four gas sources (204-208),the system (200) can include any suitable number of gas sources. The gassources (204-208) can be coupled to one or more reaction chambers (202)via lines (214-218), which can include flow controllers, valves,heaters, and the like.

The exhaust (210) can include one or more vacuum pumps.

The controller (212) includes electronic circuitry and software toselectively operate valves, manifolds, heaters, pumps and othercomponents included in the system (200). Such circuitry and componentsoperate to introduce precursors, reactants, and purge gases from therespective sources (204-208). The controller (212) can control timing ofgas pulse sequences, temperature of the substrate and/or reactionchamber, pressure within the reaction chamber, and various otheroperations to provide proper operation of the system (200).

The controller (212) can include control software to electrically orpneumatically control valves to control flow of precursors, reactantsand purge gases into and out of the reaction chamber (202). Thecontroller (212) can include modules such as a software or hardwarecomponent, e.g., a FPGA or ASIC, which performs certain tasks. A modulecan advantageously be configured to reside on the addressable storagemedium of the control system and be configured to execute one or moreprocesses.

Other configurations of the system (200) are possible, includingdifferent numbers and kinds of precursor and reactant sources, and theinclusion of one or more purge gas sources. Further, it will beappreciated that there are many arrangements of valves, conduits,precursor sources, and purge gas sources that may be used to accomplishthe goal of selectively feeding gases into the reaction chamber (202).Further, as a schematic representation of a system, many components havebeen omitted for simplicity of illustration, and such components mayinclude, for example, various valves, manifolds, purifiers, heaters,containers, vents, and/or bypasses.

During operation of the reactor system (200), substrates, such assemiconductor wafers (not illustrated), are transferred from, e.g., asubstrate handling system to reaction chamber (202). Once substrate(s)are transferred to reaction chamber (202), one or more gases from thegas sources (204-208), such as precursors, reactants, carrier gases,and/or purge gases, are introduced into the reaction chamber (202).

In some cases, it will be understood that some gasses, such as O₂, N₂,H₂, He, and Ar, are very common and are used throughout a fabrication.Accordingly, they may not be necessarily stored in a vessel inside thetool but may, instead, be provided from a central storage unit (notshown, which may be a pressurized vessel) via gas lines to a system asdescribed herein.

FIGS. 3A and 3B show structures that can be formed by way of embodimentsof methods as disclosed herein. The structure of FIG. 3A comprises asubstrate (300) on which a hard mask (310) is formed. Suitablesubstrates include silicon wafers on which one or more patterned orunpatterned layers and structures have been formed. The hard mask (310)can comprise, for example, a metal, a metal alloy, a semiconductor, analloy of several semiconductors, amorphous carbon, a nitrogen andcarbon-containing material, a metal nitride, a metal carbide, a metaloxide, or another suitable material. Suitably, and in some embodiments,the hard mask can have a thickness of at least 1.0 nm to at most 10.0nm. An underlayer (320) is positioned on the hard mask (310). Theunderlayer (320) can comprise, for example, a metal such as Sn, Sb or Inin addition to oxygen, and carbon. Thus, the underlayer (320) cancomprise a metal oxycarbide. Additionally or alternatively, theunderlayer (320) can comprise a silicon oxycarbide. The underlayer canhave a thickness of less than 10 nm or less than or about 5 nm (such as2 to 3 nm or more). Overlying the underlayer (320) is a patterned resist(330). Suitably, the patterned resist can comprise an EUV resist asdescribed herein. The patterned resist (330) comprises a plurality ofpatterned features (331) and a plurality of recesses (332), theplurality of recesses comprise sidewalls (333) and bottom portions(334).

The structure of FIG. 3B is similar to that of FIG. 3A in the sense thatit also comprises a substrate (300), hard mask (310), underlayer (320),and patterned resist (330) as described before. The difference lies inthe fact that during formation of the structure of FIG. 3B, the linerhas been anisotropically etched to form a plurality of spacers (345).The etch was an anisotropic etch as described elsewhere herein thatpreferably etches material in a direction perpendicular to thesubstrate. Since the liner is thicker at the sidewalls of the patternedresist, when looked at in a direction perpendicular to the wafer, theanisotropic etch results in formation of the aforementioned spacersstructure, and an associated reduction in the width of theaforementioned recesses. Thus, the critical dimension of patternedstructures can be advantageously reduced.

FIG. 4 shows a flow chart of an exemplary patterning method inaccordance with certain embodiments of the present disclosure. Inparticular, the method comprises a step (410) of providing a substrate.Then, the method comprises a step (420) of forming a hard mask. Then,the method comprises a step (430) of forming an underlayer. Then, themethod comprises a step (440) of forming a patterned resist. Then, themethod comprises a step (450) of forming a liner. Then, the methodcomprises a step (460) of forming a spacer.

FIG. 5 shows a flow chart of an embodiment of a method for forming aliner in accordance with certain embodiments of the present disclosure.This embodiment illustrates a thermal cyclical process of forming aliner, such as an atomic layer deposition process. The method starts(511) with an introduction of a substrate in a reaction chamber. Then,the method comprises a precursor pulse (512) that comprises introducinga precursor in the reaction chamber. Optionally, the reaction chamber isthen purged (513) using a purge gas such as a noble gas or another gasthat does not substantially react with the precursor or reactant. Then,the method comprises a reactant pulse (514) that comprises providing areactant to the reaction chamber. Optionally, the reaction chamber isthen purged (515) using a purge gas. The precursor pulse (512), thereactant pulse (514), and the optional purge steps (513,515) canoptionally be repeated (516) one more time, thus executing one or moredeposition cycles. After a pre-determined number of deposition cycleshas been executed, the method ends (517).

In an exemplary embodiment of an atomic layer deposition process offorming a liner as described herein the metal precursor comprisestetrakis(dimethylamido)tin, the reactant comprises H₂O, the substrate ismaintained at a temperature of 125° C., and the reaction chamber ismaintained at a pressure of 5 Torr.

In another exemplary embodiment of an atomic layer deposition process offorming a liner as described herein the metal precursor comprisestrimethylindium, the reactant comprises H₂O, the substrate is maintainedat a temperature of 125° C., and the reaction chamber is maintained at apressure of 5 Torr.

FIG. 6 shows another flow chart of an embodiment of a method for forminga liner in accordance with certain embodiments of the presentdisclosure. This embodiment illustrates a thermal chemical vapordeposition process of forming a liner. The method starts (611) with anintroduction of a substrate in a reaction chamber. Then, the methodcomprises a step (612) introducing a precursor and optionallyintroducing a reactant in the reaction chamber. Thus, a liner is formedon the substrate. After the substrate has been exposed to precursor andoptionally to reactant for a pre-determined amount of time, the methodends (613).

FIG. 7 shows a flow chart of another embodiment of a method for forminga liner in accordance with certain embodiments of the presentdisclosure. This embodiment illustrates a cyclical process of forming aliner. In this embodiment, the cyclical process comprises generating aplasma such as a remote plasma, an indirect plasma, or a direct plasma.Suitable plasma-enhanced processes include plasma-enhanced andradical-enhanced atomic layer deposition process. The method starts(711) with an introduction of a substrate in a reaction chamber. Then,the method comprises a precursor pulse (712) that comprises introducinga precursor in the reaction chamber. Optionally, the reaction chamber isthen purged (713) using a purge gas such as a noble gas or another gasthat does not substantially react with the precursor. Then, the methodcomprises a plasma pulse (714) that comprises generating plasma. Theplasma can be generated in the reaction chamber itself without anyseparators between the plasma and the substrate, which is called adirect plasma configuration. Alternatively, the plasma can be generatedin the reaction chamber itself with a separator between the plasma andthe substrate, which is called an indirect plasma chamber. As yetanother alternative, the plasma can be generated in a separate plasmachamber which is located at a certain distance, e.g. of at least 0.2 m,from the reaction chamber; which is called a remote plasmaconfiguration. Regardless of the specific configuration, the plasmapulse (714) comprises exposing the substrate to plasma-generated speciessuch as ions or radicals. Optionally, the reaction chamber is thenpurged (715) using a purge gas. The precursor pulse (712), the plasmapulse (714), and the optional purge steps (713,715) can optionally berepeated (716) one more time, thus executing one or more depositioncycles. After a pre-determined number of deposition cycles has beenexecuted, the method ends (717).

FIG. 8 shows yet another flow chart of an embodiment of a method forforming a liner in accordance with certain embodiments of the presentdisclosure. This embodiment illustrates a plasma-enhanced chemical vapordeposition process of forming a liner. The method starts (811) with anintroduction of a substrate in a reaction chamber. Then, the methodcomprises a step (812) introducing a precursor in the reaction chamberwhile generating a plasma. Various plasma configurations are possiblesuch as the direct, indirect, and remote plasma configurations describedherein. Thus, a liner is formed on the substrate. After precursorexposure and plasma generation has occurred for a pre-determined amountof time, the method ends (813).

FIGS. 9A, 9B, and 9C show exemplary pulsing schemes that can be used forforming liners in one or more embodiments of methods as describedherein. In each of these embodiments, a plasma can be optionallygenerated, and could be used, for example in a direct, indirect, orremote configuration. The plasma can be operated continuously or in apulsed manner. FIG. 9A shows a flow scheme in which precursor andreactant are continuously provided to the reaction chamber, i.e. thereis no pulsing of precursor or reactant flow. Both thermal andplasma-enhanced chemical vapor deposition methods can employ such acontinuous precursor or reactant provision. FIG. 9B shows a flow schemein which precursor flow is pulsed and reactant flow is continuous. FIG.9C shows a pulsing scheme in which precursor flow is continuous andreactant flow is pulsed. The flow schemes of FIGS. 9B and 9C can be usedin pulsed thermal or plasma-enhanced chemical vapor depositionapproaches of forming a liner.

FIGS. 10A and 10B show further exemplary pulsing schemes that can beused for forming liners in one or more embodiments of methods asdescribed herein. In both the embodiments of FIGS. 10A and 10B, thesubstrate is exposed to precursor and reactant in non-overlappingprecursor pulses and reactant pulses, respectively. Optionally, theprecursor pulses and the reactant pulses are separated by purges. Insome embodiments (not shown) the precursor and reactant pulses partiallyoverlap. In the embodiment of FIG. 10A, a plasma is generated, and couldbe used, for example, in a direct, indirect, or remote configuration.During the plasma pulses, the substrate is exposed to plasma-generatedactive species such as ions or radicals. In some embodiments, the plasmapulses at least partially overlap with at least one of the precursorpurses and the reactant pulses. In the embodiment shown, the plasmapulses overlap with the reactant pulses, i.e. the plasma is generated atthe same time as the reactant is provided. The embodiment of FIG. 10Bshows a thermal process in which no plasma is used for forming theliner. FIG. 11 shows a schematic representation of an embodiment of adirect plasma system (1100) that is operable or controllable to performthe fabrication processes or methods as described herein. The system(1100) includes a reaction chamber (1110) in which a plasma (1120) isgenerated. In particular, the plasma (1120) is generated between ashowerhead injector (1130) and a substrate support (1140) supporting asubstrate or wafer (1141).

In the configuration shown, the system (1100) includes two alternatingcurrent (AC) power sources: a high frequency power source (1121) and alow frequency power source (1122). In the configuration shown, the highfrequency power source (1121) supplies radio frequency (RF) power to theshowerhead injector, and the low frequency power source (1122) suppliesan alternating current signal to the substrate support (1140). The radiofrequency power can be provided, for example, at a frequency of 13.56MHz or higher. The low frequency alternating current signal can beprovided, for example, at a frequency of 2 MHz or lower.

Process gas comprising precursor, reactant, or both, is provided througha gas line (1160) to a conical gas distributor (1150). The process gasthen passes via through holes (1131) in the showerhead injector (1130)to the reaction chamber (1110). Whereas the high frequency power source(1121) is shown as being electrically connected to the showerheadinjector and the low frequency power source (1122) is shown as beingelectrically connected to the substrate support (1140), otherconfigurations are possible as well. For example, in some embodiments(not shown), both the high frequency power source and the low frequencypower source can be electrically connected to the showerhead injector;both the high frequency power source and the low frequency power sourcecan be electrically connected to the substrate support; or both the highfrequency power source can be electrically connected to the substratesupport, and the low frequency power source can be electricallyconnected to the showerhead injector.

FIG. 12 shows a schematic representation of another embodiment of anindirect plasma system (1200) operable or controllable to perform themethods as described herein. The system (1200) includes a reactionchamber (1210), which is separated from a plasma generation space (1225)in which a plasma (1220) is generated. In particular, the reactionchamber (1210) is separated from the plasma generation space (1225) by ashowerhead injector (1230), and the plasma (1220) is generated betweenthe showerhead injector (1230) and a plasma generation space ceiling(1226).

In the configuration shown, the system (1200) includes three alternatingcurrent (AC) power sources: a high frequency power source (1221) and twolow frequency power sources (1222), (1223) (i.e., a first low frequencypower source (1222) and a second low frequency power source (1223)). Inthe configuration shown, the high frequency power source (1221) suppliesradio frequency (RF) power to the plasma generation space ceiling, thefirst low frequency power source (1222) supplies an alternating currentsignal to the showerhead injector (1230), and the second low frequencypower source (1223) supplies an alternating current signal to thesubstrate support (1240). A substrate (1241) is provided on thesubstrate support (1240). The radio frequency power can be provided, forexample, at a frequency of 13.56 MHz or higher. The low frequencyalternating current signal of the first and second low frequency powersources (1222), (1223) can be provided, for example, at a frequency of 2MHz or lower.

Process gas comprising precursor, reactant, or both, is provided througha gas line (1260) that passes through the plasma generation spaceceiling (1226) to the plasma generation space (1225). Active speciessuch as ions and radicals generated by the plasma (1220) from theprocess gas pass via through holes (1231) in the showerhead injector(1230) to the reaction chamber (1210).

FIG. 13 shows a schematic representation of an embodiment of a remoteplasma system (1300) operable or controllable to perform the fabricationmethods or processes as described herein. The system (1300) includes areaction chamber (1310), which is operationally connected to a remoteplasma source (1325) in which a plasma (1320) is generated. Any sort ofplasma source can be used as a remote plasma source (1325), for examplean inductively coupled plasma, a capacitively coupled plasma, or amicrowave plasma. In particular, active species are provided from theplasma source (1325) to the reaction chamber (1310) via an activespecies duct (1360) to a conical distributor (1350) via through holes(1331) in a shower plate injector (1330) to the reaction chamber (1310).Thus, active species can be provided to the reaction chamber in auniform way.

In the configuration shown, the system (1300) includes three alternatingcurrent (AC) power sources: a high frequency power source (1321) and twolow frequency power sources (1322, 1323) (e.g., a first low frequencypower source (1322) and a second low frequency power source (1323)). Inthe configuration shown, the high frequency power source (1321) suppliesradio frequency (RF) power to the plasma generation space ceiling, thefirst low frequency power source (1322) supplies an alternating currentsignal to the showerhead injector (1330), and the second low frequencypower source (1323) supplies an alternating current signal to thesubstrate support (1340). A substrate (1341) is provided on thesubstrate support (1340). The radio frequency power can be provided, forexample, at a frequency of 10 MHz or higher. The low frequencyalternating current signal of the first and second low frequency powersources (1322), (1323) can be provided, for example, at a frequency of 2MHz or lower.

In some embodiments (not shown), an additional high frequency powersource can be electrically connected to the substrate support. Thus, adirect plasma can be generated in the reaction chamber. Process gascomprising precursor, reactant, or both, is provided to the plasmasource (1325) by means of a gas line (1360). Active species such as ionsand radicals generated by the plasma (1320) from the process gas areguided to the reaction chamber (1310).

The example embodiments of the disclosure described above do not limitthe scope of the invention, since these embodiments are merely examplesof the embodiments of the invention. Any equivalent embodiments areintended to be within the scope of this invention. Indeed, variousmodifications of the disclosure, in addition to the embodiments shownand described herein, such as alternative useful combinations of theelements described, may become apparent to those skilled in the art fromthe description. Such modifications and embodiments are also intended tofall within the scope of the appended claims.

We claim:
 1. A method for forming a structure, the method comprising thesteps of: providing a substrate to a reaction chamber, the substratecomprising a patterned resist, the patterned resist comprising a firstmetal, the patterned resist further comprising a plurality of patternedfeatures and a plurality of recesses, the plurality of recessescomprising sidewalls and bottom portions; and forming a liner on thesidewalls, wherein the liner comprises a second metal.
 2. A method forforming a pattern on a substrate, the method comprising the steps of:forming a resist on a substrate, the resist comprising a first metal;partially exposing the substrate to radiation through a mask, therebyforming exposed resist portions and unexposed resist portions;selectively removing one of the exposed resist portions and unexposedresist portions, thereby forming a patterned resist, the patternedresist comprising the first metal, the patterned resist furthercomprising a plurality of patterned features and a plurality ofrecesses, the plurality of recesses comprising sidewalls and bottomportions; providing the substrate to a reaction chamber; and forming aliner on the sidewalls, wherein the liner comprises a second metal. 3.The method according to claim 1, wherein the resist comprises an EUVresist and the radiation comprises EUV radiation.
 4. The methodaccording to claim 1, wherein the first metal and the second metal arethe same.
 5. The method according to claim 1, wherein the liner isfurther formed on the patterned features and the bottom portions of therecesses.
 6. The method according to claim 5, wherein the step offorming the liner is further followed by etching the liner, therebyremoving the liner from the patterned features and the bottom portionsof the recesses, and forming spacers on the sidewalls.
 7. The methodaccording to claim 6, wherein at least one of the first metal and thesecond metal is selected from Sn, In, Sb, Ti, Al, Zn, Hf, and Zr.
 8. Themethod according to claim 1, wherein the liner and the resist have asubstantially identical composition.
 9. The method according to claim 1,wherein the liner and the resist have a substantially identical etchrate.
 10. The method according to claim 1, wherein at least one of theresist and the liner comprise one or more of a pnictogen, a chalcogen,and a halogen.
 11. The method according to claim 10, wherein the resistand the liner comprise the same metal oxide.
 12. The method according toclaim 1, wherein forming the liner comprises providing a precursor and areactant to the reaction chamber.
 13. The method according to claim 12,wherein forming the liner comprises forming a plasma.
 14. The methodaccording to claim 12, wherein the precursor and the reactant aresimultaneously provided to the reaction chamber.
 15. The methodaccording to claim 12, wherein forming the liner comprises a cyclicalprocess, wherein the cyclical process comprises a precursor pulse and areactant pulse, wherein the precursor pulse comprises exposing thesubstrate to the precursor, and wherein the reactant pulse comprisesexposing the substrate to the reactant.
 16. The method according toclaim 12, wherein the precursor comprises at least one of a metalalkylamine, a metal alkyl, and a metal halide.
 17. The method accordingto claim 12, wherein the reactant comprises oxygen.
 18. A systemcomprising one or more precursor source, a reaction chamberoperationally coupled with the one or more precursor sources, and acontroller, the controller being arranged for causing the system tocarry out a method according to claim
 1. 19. A structure comprising asubstrate, a patterned resist, and a liner; the patterned resistcomprising a first metal, the patterned resist further comprising aplurality of patterned features and a plurality of recesses, theplurality of recesses comprising sidewalls and bottom portions; and theliner being positioned on the sidewalls, wherein the liner comprises asecond metal.
 20. The structure according to claim 19 being formed by amethod comprising the steps of: providing a substrate to a reactionchamber, the substrate comprising a patterned resist, the patternedresist comprising a first metal, the patterned resist further comprisinga plurality of patterned features and a plurality of recesses, theplurality of recesses comprising sidewalls and bottom portions; andforming a liner on the sidewalls, wherein the liner comprises a secondmetal.